CPT Error - Source and destination

[Gotxreddragonx]

Hello, I am having trouble with the CPT in RSLogix 500, with a ML1400. At first I had everything in one equation, it gave me the Source and destination may not be an immediate error and a couple others. So I split the equation up into three separate rungs. I eliminated all of the errors except the Source and destination may not be an immediate, and it was only on the one equation.

Here is what I have: CPT F8:22 102.0 * ( F8:10 ** ( 3.0 | 2.0 ) )

I tried replacing F8:22 with N7:0 and F8:10 with an actual number. Nothing seems to work.

F8:10 is for the head of water over a weir, and will be determined using a level sensor, and needs to be to the 3/2 power.

 

[Mispeld]

This is a guess...the problem may be with the power term (3.0 | 2.0). With RS-Logix 5, not 500, the description of the XPY (X to the power of Y) instruction is explicit about the operands being addresses, and not immediate values.

Try putting the value 1.5 in another F register (e.g., F8:11 if available) and changing the compute to: CPT F8:22 102.0 * (F8:10 ** F8:11).

 

[Mickey]

CPT F8:22 102.0 * ( F8:10 ** ( 3.0 | 2.0 ) )

Is the above how you wrote the expression?

Is 102.0 the value in F8:22 or is it a constant in your expression? If so there is no operator between the two.

 

[Gotxreddragonx]

The 102.0 is a constant, multiplied by the product pf F8:10 to the power of 3/2. I'll try the 3/2 power stored in another float register

 

[MikeyN]

http://www.plctalk.net/qanda/archive/index.php/t-61094.html

At the bottom of this thread, TConnolly mentions that you cannot multiply two constants. This may the be same problem you are having. In a test copy i checked offline, I added 1.5 to F8:20 and replaced the 3/2 with F8:20. The program verified fine.

 

[Gotxreddragonx]

Thanks Mikey, I tried searching for the error but nothing turned up. I figured someone had to of had the same issue before. That did fix my issue though. Thanks again everyone!